[services] Tests - Add backup utils

Summary:
Depends on D4161

I'm not an expert at all in Rust crate/module system. I decided to create a separate module that's going to be fetching all necessary things and then multiple modules can take that imports from here.

Test Plan: This itself doesn't do anything.

Reviewers: palys-swm, ashoat, varun

Reviewed By: palys-swm, varun

Subscribers: ashoat, palys-swm, Adrian, atul, yayabosh

Differential Revision: https://phab.comm.dev/D4164